Electric switching arrangement



Dec. ,17, 1929. w, KEARSLEY 1,740,405

ELECTRIC SWITCHING ARRANGEMENT Filed 001'. 2'7, 192'! Inventor: William K. Kearsleg,

His Attorney.

Patented Dec. 17, 1929 UNITED STATES PATENT OFFICE WILLIAM K. KEARSLEY, OF SCHENEC'I'ADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, .A. CORPORATION OF NEW YORK ELECTRIC SWITCHING ARRANGE-Mm! Application filed October 27, 1921. Serial No. 229,218.

My invention relates to improvements in electric switching arrangements and particularly to improvements in switching arrangements for controlling the connection of one circuit to another whereby the duration of the connection can be closely varied and accurately timed and especially the connection of two alternating current circuits whereby their connection, disconnection, or both may be effected when the instantaneous value of one of the electric quantities of one circuit, such as the current or the voltage is substantially zero.

My invention will be better understood from the following description when considered in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

The sin le figure of the accompanying drawing ifiustrates an embodiment of my invention as applied to the timing control of an X-ray tube 1 for which it is particularly adapted because of uniformity of timing especlally for short exposures and the fact that heavy currents can be interrupted without arcing. It is, however, to be understood that my invention is not so limited. For controlling the duration of energization of the anodecathode circuit of the tube 1, I provide in accordance with my invention an electric switch 2 which is arranged to control the connection of a supply circuit 3 to a load circuit 4 including the primary of a transformer 5 for providing the tube 1 with the necessary high voltage. As shown the switch 2 comprises two independent movable contact members such as the pairs of contacts 6, 7 which are arranged to engage coo crating contacts 8, 9 connected in series in t e load circuit. The circuit opening movement of the contacts 6, 7 ma be limited in any suitablemanner as by a justably positioned stops 60, 70.

- For effecting the movement of the contacts 6, 7 to the circuit closing position and main-' tainin them in this position a predetermined time, provide means comprising a synchronous motor 10 which is connected to be energized from the single phase supply circuit 3 and which is arranged to operate contact actuating means whereby the opening or closirtilg of the single phase load circuit 4 can be e ected when the instantaneous value of the load circuit current or supply circuit voltage ated with the respective contacts 6, 7 and biased for example by gravity and springs 15 so as to be held against their respective cams, actuating members such as cranks 16, 17 secured to their respective contacts 6, 7, and means-such as latches 18, 19 pivotally mounted on the cranks 16, 17 for interlocking the cranks andtheir respective arms 13, 14. The cams 11, 12 as shown may be of circular outline and are eccentrically suitably secured to a shaft 20 so that the position of each relatively to the other can be varied to chan 'e the duration of closure of the contacts 6, 7 and so that the position of each relatively to the rotor of the motor 10 can be varied to effect the opening, closing, or both of the load circuit 4 at a predetermined point in the current or voltage wave of the supply circuit. In a specific embodiment of my mvention the parts are so proportioned for use on a 60-cycle current circuit that the marks on the shaft '20 are substantially 18 apart and correspond to 1/120 second or 1/2 cycle so that timing with substantially zero current at make and break may be obtained in multiples of a half-cycle. One way in which these marks ma be positioned is to set up the switch mechanism to control a circuit, each cam 11, 12 having a suitable mark such as the arrow indicated on the hub thereof and then to operate the mechanism changing the position of the cams until no noticeable arcing occurs either at make or break. The shaft 20 may then be graduated with half-cycle marks, the spacing of which will, of course, be dependent on the frequency of the circuit 3 (speed of the syngears tive follower arms 13, 14 to move together, I provide means such as electromagnets 21, 22 which are arranged to be energizedfrom a source 23 and whose circuits, as shown, are arranged to be controlled by a suitable switch 24. This switch may be manually operated and, as shown, serves to initiate the operation of the X-ray tube 1 as will hereinafter more fully appear. The latches 18, 19 are biased to t e releasing position by suitable means such as springs 25 and can be moved to interlock the respective cranks and arms only when the arms are on the low oints of the cams. In order to prevent a rec osure of the load circuit in case theswitch, 24 is maintained closed, one of the latch actuating means may be rendered ineffective after its associated contact has been closed. For this purpose suitable means such as a switch 26 arranged in the path of movement of an arm 27 movable with the pair of contacts 6 may be arran ed to be opened after the contacts are closed. The contacts 6 and 7 are referably resiliently mounted for bias to t 1e circuit o 'ning position and so as to permit a limite movement of the arms 16, 17 while the associated contacts are closed. The amount of the circuit opening movement of the contacts 6, 7 is determined by stops.

In explaining the operation of the illustrated embodiment of my invention, it will be assumed that each of the cams 11, 12 is set opposite graduations arranged relatively to the rotor of the synchronous motor 10 so that the contact closing and opening occur when the current is substantially zero and further that the cams are set relatively to each for a number of graduations corresponding to the number of half-cycles or time of ex osure desired. The direction of rotation 0 the cams is as indicated by the arrows 28 thereon. It is also assumed that the operator has closed the switch 26 and a switch, not shown, in the supply circuit 3 so as to energize the motor 10. Then the operator closes the switch 24 and holds it closed. This energizes both electromagnets 21, 22 which try to pull their associated latches 18, 19 into latching position. When the follower arm 13 meets the low point of its cam 11, the latch 18 under the pull of the electromagnet 21 slips over the top of the follower arm 13 and looks it to i the crank 16. Further movement of the cam 11 results in the closing of contacts 6, 8 and the opening of the switch 26, but the friction between the latch 18 and the follower arm 13 maintains the latch in looking position until the opening bias on the contacts 6 is reduced. In the meantime,-the'lowest point on the cam 12 is presented to the follower arm 14 which becomes locked to its-crank 17 in the same manner described for the arm 13 and the crank 16. As the cams continue to turn the contacts 7 are caused to engage the contacts 9 prior to the opening of the contacts 6, 8. Upon further rotation of the cams, the contacts 6 and 8 are cams, the contacts 7 are moved to the circuit open position and while they can be reclosed if the operator continues to hold the switch 24 closed, the load circuit 4 will not be reclosed since the contacts 6 are free of the follower arm 13. The position of the cams 11, 12 at the instant of closing the switch 24 is immaterial, for. if the crank 17 and its follower arm 14-are interlocked prior to the interlockin of the crank 16 and its follower.

arm 13, t e'contacts 7, 9 will be closed and then opened prior to the interlocking of the crank 16 and 1ts follower arm 13. Since, however, the electromagnet 22 remains energized the contacts 7, 9 will be reclosed, but only after the interlocking of the crank 16 and the 'arm 13 and the subsequent closing of the contacts 6, 8.

While I have shown and described my invention in considerable detail, I do not desire to-be limited to the exact arrangement shown, but seek to cover in the appended claims all those modifications that fall within theitrue spirit and sco e of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch for controlling the connection of two alternating current circuits comprising two independent movable contacts and means for effecting the movement of the contacts to circuit closing position and maintaining them in said position for a predetermined time comprisin a s nchronous motor connected to be energlzed rom one of the circuits, and actuating means arran ed to be operated by the motor to effect the c osing of the contacts and positioned relatively to the rotor of the motor to effect the opening of one of the contacts when the instantaneous value of the current in the circuit through the contacts is substantially zero.

2. An electric switch" for controlling the connection of two alternating current circuits comprising two independent movable contacts and means for effectin the movement of the contacts to circuit closing position and maintaining them in said position for a predetermined number of cycles of the current in one of the circuits comprising a synchronous ins motor connected to be energized from the other of said circuits, and actuating means arranged to be operated by the motor and positioned to effect the closing of one of the contacts after the closing of the other contact and when the instantaneous value of the ,voltage in said other circuit is substantially zero and positioned to effect the opening of said other contact when the instantaneous value of the current in said one of said circuits is substantially zero.

3. A switch for controllin the connection oftwo electric circuits comprising a plurality of movable contacts, means for effecting the movement of the contacts to the circuit closin position comprising a motor connected to e energized from one of the circuits, cam mechanism for actuating said contacts arranged to be driven by said motor, follower members for said contacts arranged to be actuated by the cam mechanism, and means for interlocking a follower member with its associated contact when the cam mechanism is in a predetermined position whereby to effect the movement of the contact to the circuit closing position.

4. A switch for controlling'the connection of two electric circuits comprising a plurality of movable contacts, means for efiecting the movement of the contacts to the circuit closin position comprising a motor connected to be energized from one of the circuits, cam mechanism for actuating said contacts arranged to be driven by said motor, follower members for said contacts arranged to be actuated by the cam mechanism, means arranged to be energized to interlock a 01- lower member with its associated contact when the cam mechanism is in a predetermined position whereby to efiect the movement of the contact to the circuit closing position, and means for eiiecting the deenergization of said interlocking means after the contact is in the circuit closing position.

5. In combination with two alternating current circuits, means for controlling the connection of the circuits comprising two independent movable contact members and means for elfecting the movement of themem bers to circuit closing position and maintaining them in said position for a predetermined time comprising a synchronous motor connected to be energized from one of the circuits and actuating means arranged to be operated by themotor and positioned to effect the closing of one of the contact members after the closing of the other contact member and to effect the o ,ening of said other contact mem her when t 1e instantaneous value of the current in the other of said circuits has a predetermined value.

6. In combination with two alternating current circuits, means for controlling the connection of the circuits comprising two independent movable contact members and means for effecting the movement of the members to circuit closing position and maining them in said position for a predetermined time comprising a synchronous motor connected to be energized from one of the 011- cuits and actuating means arranged to be operated by the motor and positioned to e ect the closing of one of the contact members after the closing of the other contact member and when the instantaneous value of one of the electric quantities of the circuit through said contacts is substantially zero.

7. In combination with a single phase'load circuit and a single phase supply circuit,

means for controlling the connection of the circuits comprising two independent movable contacts, and means for effecting the movement of the contacts to circuit closing position and maintainin them in said position for apredetermine time comprisin a single phases nchronous motor connecte to be energized. rom the supply circuit, and actuating means arranged to be operated by the motor to efiect'the closing of the contacts and positioned relatively to the rotor of the motor to effect the opening of one of the contacts when the instantaneous value of the load circuit current is substantially zero.

8. In combination with a load" circuit and an alternating current supply circuit, means for controlling the connection of the circuits comprising two independent movable contact members, and means for effecting the movement of the members to circuit closing position and maintaining them in said positlon for a predetermined number of cycles of the supply current comprising a s nchronous motor connected to be energize from the supply circuit, and actuating means arranged to be operated by the motor and positioned to effect the closing of one of the contact members after the closing of the other contact member and when the instantaneous value of the supply circuit voltage is substantially zero and to effect the opening of said other contact member when the instantaneous value of the load circuit current is substantially zero.

9. An electric switch for controlling the connection of two alternating current circuits comprising a plurality of independent movable contacts biased for movement to the. circuit open position and means for efl'ecting the movement of the contacts to the circuit closing position comprising a synchronous motor connected to be energized from one of the circuits, cam mechanism for actuating said contacts arranged to be driven by said motor, follower arms for said contacts arranged to be actuated by the cam mechanism, and electromagnetic means for interlocking a follower arm with its associated contact when the cam mechanism is in a predetermined position whereby to effect the movement of the contact to the circuit closing position.

10. An electric switch for controlling the connection of two alternating current circuits comprising a plurality of independent movable contacts biased for movement to the circuit open position and means for efi'ecting the movement of the contacts to the circuit closing position com rising a chronous motor connected to e energize from one of the circuits, cam mechan1sm;,for actuating said contacts arranged tov be driven by said motor, follower armsfor said contacts arranged to be actuated by the cam mechanism, electromagnetic means arranged upon 10 energization-to interlock a follower arm with its associated contact when the cam mecha-A nism is in a predetermined osition whereby to effect the movement of t e contact to the circuit closing position, and means for effecting the deenergization of the electromagnetic interlocking means associated with one of the contacts after the contact is closed.

In witness whereof, I have hereunto set my hand this 26th da of October, 1927.

. WIL IAM K. KEARSLEY. 

